>Does it make things more clear to you? yes, that's exactly what I needed.
>PS: I still hate Expression(?) since with a little more thought one can almost always do better (and in the end faster). I have the same feeling, but I guess that might require mathematical knowledge and level of abstraction I don't posses by now. To make things clear I want to solve Hamiltonian equations. And I want to do it using formal solution involving exponent of an operator. http://en.wikipedia.org/wiki/Symplectic_integrator formula (3) is that formal solution. And I need approximation of this exponent to be done symbolically since employing numerical differentiation operator promises to be a pain. So at least I need to deal with a Hamiltonian. My current knowledge allows me to think Hamiltonian only to be the function ℝ × ℝ × … × ℝ → ℝ. Unfortunately I don't know differential geometry yet to be able to reformulate the problem. Since it seems I can't deal with the Hamiltonian as a function ℝ × ℝ × … × ℝ → ℝ within FriCAS I have to prescribe it Expression(Float) type. Hence as I need { · , H} operator ( { · , · } being Poisson bracket) I force to have Poisson bracket of type (Expression(...), Expression(...) ) -> Expression(...) >After that my next question will be: How can that be made algorithmic in general? You probably want an answer in finite time. Or would you accept approximate values for this "exp"? Yes approximate will do, ultimately all these symbolic stuff is required to produce a numeric functions. So its not to be some real exponent, but rather a finite term series (at least ~32 terms in the series). Well, lets call it MyExp to avoid confusion. >Now what should be the type of this exp operation. Please avoid Expression(...). It's a serious question. Something like a -> a and since its argument f +-> {f,H} by now has the type of Expression(...) -> Expression(...) nothing left except MyExp : Expression(..) -> Expression(..) -- You received this message because you are subscribed to the Google Groups "FriCAS - computer algebra system" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/fricas-devel?hl=en.
